cq5 - How to collect new urls which has been found in new version -

i urls author added in new version of page.

example: author adds www.url1.com in mypage , activate mypage. --> version 1.0 generated author adds www.url2.com in mypage , activate mypage. --> version 1.2 generated -> mypage version 1.2 has bouth www.url1.com , www.url2.com

the function has return www.url2.com in case.

i wrote function getnewurls(set>string> urls) collects urls old version , new version , deletes old found urls new found urls follow.

private set<string> getnewurls(set<string> urls){    set<string> newurls = collecturlsfromnodes(newversionnode.getnodes());    set<string> oldurls = collecturlsfromnodes(oldversionnode.getnodes());    set<string> mynewurls newurls.removeall(oldurls);  }  private set<string> collecturlsfromnodes(final nodeiterator nodeiter) {          set<string> urlset = new hashset<string>();         while (nodeiter.hasnext()) {             node subnode = nodeiter.nextnode();             urlset.addall(collecturlsfromnodes(subnode.getnodes()));             if (subnode.hasproperty("filereference")) {                 string url = subnode.getproperty("filereference").getstring();                 urlset.add(url);             }         }         return urlset;     } 

prolbem function find urls, author deleted (mybe because still stored in content when author delete/edit urls page). idea how solve problem?